Intermitting system for flowing wells



March 2, 1943- l.. M. TRAwlcK l INTERMITTING SYSTEM FOR FLOWNG WELLSFiled sept. 3, 1940 2 Sheets-Sheet .L

o/o y Rw M w /Mwwww m c@ f w wm mwm; g J BK A March 2, 1943. L, M,TRAwlcK l l INTERMITTING SYSTEM FOR FLOWING WELLS 'Filed Sept. 3, 19110A2 Sheets-Sheet 2 .III

III..

INVENT Patented Mar. 2, 1943 INTERMITTING SYSTE WELLS FOR FLOWING LynnM. Trawick, Stroud, Okla.

Application September 3, 1940, Serial No. 355,274

(Cl. 10S-233) 15 Claims.

This invention relates to the flowing of liquid from wells and moreparticularly, but not by way of limitation to an automatic intermittingapparatus for controlling the admission of a gas under pressure into acolumn of liquid to raise the liquid out of the well. This applicationcontains subject matter disclosed but not claimed in applicantsco-pending application, Serial No. 355,273, filed September 3,1940,patented July 14, 1942, No. 2,289,603.

In the pneumatic displacement or gas lifting of liquid from oil wells,mechanical devices such as kick off, flow or starting valves for flowingthe well have been used in wells where the bottom hole pressure isinsufficient to provide a natural flow to raise the liquid level to thesurface. With the event of proration in most of the oil bearing states,intermitting systems for flowing the Wells have been utilized wherein aliquid is displaced through the eduction tubing by injecting gas througha selectively disposed valve at timed intervals, the operation of thevalve being affected by a time signal control installation at the top ofthe Well.

Heretofore, mechanical installations for the displacement of oil fromwells has disregarded to a great extent the importance of gas lifting asan aid to preserving the bottom hole pressure or formation energy of thewell. Furthermore, little consideration has been given the gas-oil ratioin producing the well since the motive fluid or input gas in usuallyinjected into the well at sufficiently high pressures to ilow the wellunder any condition, which obviously in many instances causesunnecessary waste or use of motive fluid.

The present invention utilizes the arrangement of a plurality ofautomatic kick off or flow valves whose operation is based on theprinciple of constant submergence pressure. By constant submergencepressure is meant the pressure as determined by calculating the numberof feet of liquid which the motive fluid operating in the well willsuspend, minus the distance from a particular valve receiving the motivefluid to the liquid level below which the valve is arranged.

It is therefore an important object of this invention to provide meansfor controlling the admission of motive fluid under pressure into acolumn of liquid to raise the same from a well.

Another object of this invention is to provide means which will controlthe admission of motive Huid into a column of liquid in such a mannerthat the control means is governed by the hydrostatic pressure due tothe column of oil.

A further object of this invention is to provide a fluid liftingassembly of an entirely automatic intermitting type which will besubject in its operation to the pressure of the column of liquid in thewell, and to the motive fluid utilized in flowing the wen.

Another object of this invention is to provide a plurality ofdifferential type fluid controlling valves having a dual seatingarrangement, Whereas a valve is moved to a neutral position either bythe hydrostatic level of the fluid or the pressure of the input gas,depending upon in which position the valve is seated.

An additional object of this invention is to provide an automaticintermitting apparatus arranged in the eduction tubing employed in theflowing of liquid from a well in such a manner that the apparatus actsas a choke for decreasing the volume of liquid to be lifted, therebyconserving the amount of motive fluid necessary to lift the liquid.

A further object of this vinvention is to provide an automaticintermitting apparatus in the eduction tubing employed in the flowing ofliquid from an oil well, said apparatus including a plurality of controlunits determining the flow of liquid into the tubing, as well asdischarging the liquid into the eduction tubing in a vertical upstreamdirection in order to prevent any distortion or turbulence of liquidbelow a control unit.

And still an additional object of this invention is to provide anautomatic intermitting apparatus arranged in the eduction tubing of awell so as vto provide a proper gas-oil ratio by displacing as muchliquid as possible with as little use of motive fluid as is economicallyfeasible. Furthermore, the motive fluid is directed in a verticalupstream from the intermitting apparatus to prevent any pressure actingagainst the oil not being lifted and preventing any counterforcedisturbing the normal back pressure of the well.

Other objects and advantages of the invention will be evident from thefollowing detailed description read in conjunction with the accompanyingdrawings which illustrate one form of my invention.

In the drawings:

Fig. 1 is a fragmentary vertical sectional view with certain parts inelevation of the intermitting system shown disposed in a well hole.

Fig. 2 is an enlarged front elevational view of one of the lower valvecollars and valve unit associated therewith.

Fig. 3 is an enlarged vertical elevational view of the collar and valveunit shown in Fig. 2. V

Fig. 4 is a View similar to Fig. 1 with the surface shown disposed inthe well with the lower end in`v proximity of the shot hole 4. The upperend of.. the casing 2 is secured to a suitable casing head 8 cooperatingwith an apertured tubing head |0 suspending a string of tubing 6 inspaced relation to the casing 2.

The casing head s is provided with ports l2` and |4 receiving conduitsI6 and I8 respectively. A tubing head T is disposed above head |0randreceives conduits 24 and'rr26 "respectivelyr A*rl/'heV conduit ,24isconnected by the {T-connectionZ- tonoonduit I6.,A However, a suitablevalve is interposed in line 24 for Vcontrolling the `flow of fluidthrough Vconduit 24. Valves 32 and 34fare interposed inline I6 onopposite sides of'Tconnection 28 for determining flow through' conduitI6. Apressure gauge 36 is interposed in line I6. Conduitl is providedfwith'valvfe 4 0 determining flowtherethrough,V while condit'ZGl isprovided with a valve 42 closing olf or allowing discharge' of fluidtherethrough;Y From the abovef'it will be apparent that the actuating'uid from any suitable source (not shown) can be directed into the well,either into the casing 2 or the' tubing 6,

depending upon 4regulation of AValves A30; 32fandai.V oni die 'otherhand; the' iijtebelifteq from the well may be discharged through rthecasing 2 or tubing 6 depending upon regulationA of the VallYS. and 4,2mY i For the purpose of this invention, it is preferred that valve 80 beclosed while valves 32v and 34 are open,allowinginotivemfluidto Ybedischarged into casing 6. A Similarly, valve 40is closed while'valve 424is open .allowing` oil to b e discharged from tubing 6 through;A conduit26v leading to-separators. storage'tanks, or the like (not shown)../.fipressure` gauge 44 isv disposed at the top of tubingheadri.'v (Y ivThe intermitting unit or system is arranged in the lower sections ofthe tubing string 6, and comprisesl a collar interposed in the tubing 6,which for practical purposes is usually at a point from Iifty to onehundred feet abovethe normal liquid level of the well. The collar 50, asclearly shown in detailin Fig. 6, is provided with acentraily disposedspider' 52 having av vertical threaded passagewayor bore 54. The boreY54- intersects with a transverse passageway or bore 56 providingcommunication therebetween. Sleeves or bushings 51 are threadedlysecured at opposite ends of the passageway.

As clearly shown in Figs. 1 and 5, the upper portion of bore 54 receivesa cylindrical housing 58 containing an intermittingV valve unit'to belater described. A string of smaller sizedl tubing 60 is secured inthelower portion of -the bore 56 and extends vertically downward fromthe collar 50 in spaced relation to an extension of eduction tubing 6extending downwardly from thecollar 50. The tubing 60 is interconnectedby aplurality of valve collars 62 (see Figs. 2 and 3b) havingassociatedV therewith adiierential valve unit 64 to beihereinafterdescribed. l As shown in Fig. 1, conventional packing 66 is disposedbetween the tubing 6 and casing 2 immediately below the collar 50 toblock off incoming gas pressure from the shot hole. The disposition ofthe packing provides a denite directional flow of input pres.. sure gasthrough the passageways 56 of the collar 50 for a purpose to behereinafter described. The lower end of the tubing 60 is closed off byany conventional bull plug 68. The lowermost portion'of tubing 6 isprovided with perforations 10 to allow flow of oil therethrough, and avalve cage 12 and ball valve 14 are disposed in tubing 6 for controllingthe entrance of the oil into the tubing. The end of the tubing is closedoir by a plug 15.

"Referring to the intermitting unit in detail (Fig. 5),thehousing 58comprises two sections 16 and 18 threadedly secured together at 80. Aremovable annular valve seat 82 is disposed betweenfthe'top of cylinder16 and an annular flange 84 provided on the inner periphery of cylinder18. The seatis provided with a dual bevelledv aperture 86 cooperatingwith a pair of semi-circular members forming a dual seating valvel88`disposed on a stem 80. The stem 90 extendsrthrough an apertured valvestem guide 92 vprovided inthe interior of the cylinder 16. A helicaltension spring 94 surrounds the stem and is anchored between the lowerend of guide 92 and a pair of adjusting nuts 96 threaded on the lowerend of stem 92. The spring 94 is adjusted to provide tension to assistseating of the upper portion of valve 88 in seating position. A housing98 surrounding the spring is threaded at |00 to the guide. W A pluralityof circumferentially spaced apertures |02 provides communication betweenthe passageway 54 and valve 88. Y A cylinder I 04 is threadedly securedto the upper end of cylinder A18, and is provided with outlet apertures|06. Y y

The collars 62 connecting thesmaller sized tubing 60 areusually disposedfrom fifty to one hundred feet apart. Each of the collars 62 is providedwith a reduced portion |08 in which is disposed the vertically arrangedvalve unit 64.

A pair of valve seats |09 and I I0 are disposed in an aperture II 2provided in the collar 62. A valve stem I|4 is provided at its lower endwith a circularvalve |I6 cooperating with the seats |09 and I0. Theopposite end of the stem |I6 is provided with an enlarged portion I|8for anohoring one end of a helical spring |20. The opposite end of thespring is anchoredby a nut |22 threaded on a shaft |24 which in turn isthreadedly secured at |26 to the collar 62. A lock nut |28 preventsdisplacement of shaft |24. A cover plate |30 for the spring |28'issecured by bolts |32 to the collar 62.

In Fig. 4 the arrangement of the intermitting system is exactly as thatshown in Fig. l except that the standing Valve 14 in the lower sectionof the tubing 6 is omitted, as well as the packing 66, in order that thebottom hole pressure of the well can be utilized as a motive iluidmaintained between the tubing 6 and the casing 2 and allowed to flowinto the collar 50. It is to be understood that the lcasing 2 is closedoff at the surface of the well (not shown).

Operation In operation it is intended in either of the illustrationsshown in Figs. 1 or 4 that high pressure motive nuid such as gas or airshall be maintained at a substantiallyV constant pressure within theannular space I 40 between the tubing 6 and the casing, so as to bedischarged into the passageway 58 of the collar 59. The installation ofthe intermitting system as in Fig. 4 is such that the collar 5|) isnormally disposed above the liquid level of the well, thereby preventingany liquid flowing into passageways 5'5 and the interior of the tubing60. a

The construction of the valve unit 58 or anyone of the units 64 is vsuchthat the tension of their respective springs at all times tends to closethe valve. The seating of a valve is assisted by the hydrostatic head ofthe column of well iluid assisting the action of the spring. It will beapparent that in any valve not submerged within the well fluid the dualseating aspect of the valve allows the injected motive fluid to closethe valve against the tension of its respective spring. In aninstallation wherein the collar 5U is above the liquid level, the motiveuid maintains Valve g3 in closed position and is directed from collar 59for automatically unseating the first valve unit 64 disposed immediatelybelow the liquid level. It will be apparent that the unseating action ofa valve IIB is against the tension of a spring itil andthe hydrostatichead of the weil liquid. With the valve off its seat, motive fluid isinjected into the oil stream in an upward vertical direction, liftingthe column of liquid within the tubing. As the liquid flows upward, thehydrostatic head above the particular valve gradually falls due to thedecreased amount of liquid thereabove, therefore force exerted upon thevalve tending to hold it in closed position is obviously decreased whileat the same time the velocity of gas entering the tubing 6 will increasedue to the greater differential between the pressure existing in thetubing E and that existing in the casing 2. The `motive Huid willtherefore exert an ever increasing force upon the valve tending to closeit against the tension of spring |23 and the decreasing hydrostatic headwithin the tubing E. With sufficient depletion of the hydrostatic headthe valve unit is closed and the gas is then directed downward throughthe tubing 6i) to a valve unit VEll immediately below the last unit tofunction, where the operation is repeated. This operation is repeated inthe plurality of valve units 65 until `the liquid is lifted to a pointabove collar 5i).

The arrangement of the smaller tubing Sii and the valve units 64 in thespace |42 ,provided by the interior of the lower sections of tubing 6acts as a choke to decrease the volume in space lli2, which in turndecreases the amount or volume of liquid to be lifted by the units 64 toan elevation above the collar 50, It will thus be apparent that it willtake less amount of gas at a constant -pressure to lift the oil in space|42, thereby providing an economical and conservative use of the motivefluid. As lon 1r as the hydrostatic head is sufficient above each of thevalve units Sli, they will automatically function to lift the liquid inspace |42 to an elevation above collar 50.

As soon as the hydrostatic head of the uid above the collar 5S, plus thetension of spring Sill becomes greater than the motive fluid pressure inthe passageway 54, the lower` portion of the valve 88 will be moveddownward off its seat for allowing passage of motive uid into thecylinder E04, through ports |06 and vertically upward into the oilstream, causing it to be aerated upward to the surface of the Well.

The disposition of outlet ports |05 directs the motive fluid in avertically upward stream as well as effect-s a jetting action forincreasing the velocity of the motive fiuid discharging into theeduction tubing 6. The lifting gas discharging at below the ports. Thedirectional `path of the motive fluid does not contact the liquid belowthe ports |06, thereby preventing any counteracting force against thenatural or bottom hole pressure of the well, and thus prevents anyturbulence or distortion of the liquid standing at an elevation lowerthan the ports |66. With the liquid being caused to flow in space |44above valve unit 58, to the surface, the hydrostatic head is decreasedwhereby the lower portion of valve E3 is closed against the bevelledseat 86.

The dual seating aspect of valve S3 and each of valves ||6 prevents anunnecessary Waste of motive fluid by closing the valve and substantiallyproviding the proper gas-oil ratio necessary to lift the oil whether itbe in space |132 or |44.

From the foregoing it will be apparent that the construction andarrangement of the intermitting system is simple and efficient in thatonce the submergence level of the well fluid is known, the tension onthe various valve springs can be adjusted prior to putting the system inthe well. Furthermore, the disposition of the collar 5i) determines thesubstantially constant pressure submergence necessary to slug or flowthe liquid in space |42. For all practical purposes, in the average oilwell it requires one hundred pounds per square inch of motive iiuidpressure to displace three hundred feet of oil. If the well liquidcontains both oil and water, one hundred pounds of pressure willdisplace approximately two hundred feet. The smaller sized tubing E!)and its cooperating valve units 64 act as a choke for decreasing thevolume of space for lifting less Volume of oil which obviously decreasesthe frictional resistance of liquid iiow, as Well as conserves thevolume of gas in cubic feet for lifting a smaller volume of liquid abovethe collar 5B where it is then slugged to the surface of the well by thevalve unit 53. From the normal submergence level of the well liquid andthe disposition of the collar 5G, plus the number of valve units 64, itcan be easily determined the time it takes to elevate the liquid abovethe collar in suiiicient quantities to cause an intermitting action ofthe valve 88 for slugging the oil to the surface of the well.Furthermore, any disturbance of the natural pressure of the well iseliminated, thus providing longer life to the sand pressure andsubstantially constant submergence liquid level. The well can thus fiowcontinuously by the automatic predetermined intermitting of the systemfor iiowing the liquid to the surface under any proration requirements.

Changes may be made in the combination and arrangement of parts asheretofore set forth in the specification and shown in the drawings, itbeing understood that any modification in the precise embodiment of theinvention may be made within the scope of the following claims withoutdeparting from the spirit of the invention.

What I claim is:

l. A system for controlling the lifting of well liquid including aneductio-n tubing disposed in a well, motive iiuid inlet means interposedin the eduction tubing, intermittent means communicating with the inletmeans and controlling the admission of motive fluid into the liquid at apoint below the normal liquid level, said last mentioned means arrangedin spaced relation in the eduction tubing and providing a choke fordecreasing the volume of liquid to be lifted, differential meansnormally above the liquid level responsive to the hydrostatic head ofthe liquid being lifted for admitting motive fluidinto the eductiontubing above the differential means and causing aerating of the liquid,and means for increasing the velocity of the motive fluid discharginginto the eduction tubing. V

2. A system for controlling the lifting of well liquid including aneduction tubing disposed in a well, motive fluid inlet means interposedin the eduction tubing, intermittent means communicating with the inletmeans and controlling the admission of motive fluid into the liquid at apoint below the normal liquid level, said last mentioned means arrangedin spaced relation in the eduction tubing and providing a choke fordecreasing the volume of liquid to be lifted, differential meansnormally above the liquid level responsive to the hydrostatic head ofthe liquid being lifted for admitting motive fluid into the eductiontubing above the valve and causing aerating of the liquid, and meansdirecting the discharging motive fluid in a vertical path upward.

3. A system for the intermittent lifting of well liquid including aneduction tubing disposed in the well, motive fluid inlet meansinterposed in the eduction tubing at a point above the normal liquidlevel of the well, a plurality of differential valves communicating withthe inlet means and arranged in spaced relation in the tubing andnormally disposed below the liquid level to admit pressure fluid to theliquid in the tubing, said valves providing a choke for decreasing thevolume of liquid to be lifted, each of said differential valves having adual seating arrangement responsive to either hydrostatic head of liquidor pressure of motive fluid for controlling admission of motive fluidthrough the valves into the liquid for increasing the level thereof, anintermitting valve associated with the inlet means and responsive to anincreased liquid level for admitting motive fluid into the eductiontubing for flowing the liquid.

4. A system for the intermittent lifting of well liquid including aneduction tubing disposed in the well, motive fluid inlet meansinterposed in the eduction tubing at a point above the normal liquidlevel of the well, a plurality of differential valves communicating withthe inlet means and arranged in spaced relation in the tubing andnormally disposed below the liquid level to admit pressure fluid to theliquid in the tubing, said valves providing a choke for decreasing thevolume of liquid to be lifted, each of said differential valves having adual seating arrangement responsive to either hydrostatic head of liquoror pressure of motive fluid for controlling admission of motive fluidthrough the valves into the liquid for increasing the level thereof, anintermitting valve associated with the inlet means and responsive to anincreased liquid level for admitting motive fluid into the eductiontubing above the intermitting valve for flowing the liquid, and meansfor directing the flow of motive fluid in a vertical path upward and atan increased velocity.

5. A system for controlling the lifting of well liquid including aneduction tubing disposed in the well, a collar interposed in theeduction tubing and having an inlet passageway for motive fluid, astring of small tubing communicating with the passageway and extendingdownwardly from the collar in spaced relation in the eduction tubing, aplurality of couplings connecting sections of the small tubing, adifferential valve associated with each of the couplings, anintermitting valve arranged above the collar and communicating With thepassageway, said differential valves controlling admission of motivefluid for lifting the liquid level above the collar, said intermittingvalve responsive to the hydrostatic head of the liquid being lifted foradmitting motive fluid into the eduction tubing and causing flow of theliquid upward.

6. In a system for controlling the lifting of well liquid including aneduction tubing disposed in the well, a collar interposed in theeduction tubing permitting passage of motive fluid therethrough, aplurality of differential valves communicating with the flow passage inthe collar and disposed below the collar in spaced relation in theeduction tubing an providing a choke for decreasing the volume of spacebelow the collar, an intermitting valve communicatively associated withthe collar and normally held in seated position by the pressure of themotive fluid, said differential valves responsive to the hydrostatichead of liquid for admitting motive fluid into the liquid for increasingthe liquid level, said intermitting valve responsive to the hydrostatichead created by the increased liquid level for admitting motive fluidinto the liquid stream above the intermitting valve and causing theliquid to be aerated in the eduction tubing.

7. In a system for controlling the lifting of well liquid including aneduction tubing disposed in the well, a collar interposed in theeduction tubing permitting passage of motive fluid therethrough, aplurality of differential valves arranged below the collar in spacedrelation in the eduction tubing and providing a choke for de` creasingthe volume of space below the collar, an intermitting valve associatedwith the collar and normally held in seated position by the pressure ofthe motive fluid, said differential valves responsive to the hydrostatichead of liquid for admitting motive fluid into the liquid for increasingthe liquid level, said intermitting valve responsive to the hydrostatichead created by the increased liquid level for admitting motive fluidinto the liquid stream above the intermitting valve and causing theliquid to be aerated in the eduction tubing, and a plurality of outletports associated with the valve for directing the flow of motive uid ina vertical upstream path.

8. In a well flowing apparatus including an eduction tubing, a collarinterposed in the tubing, motive fluid inlet means in the collar, aplurality of differential valves arranged below the collar in spacedrelation in the eduction tubing and communicating with the inlet means,an intermitting valve disposed above the collar and communicating withthe inlet means, said differential valves controlling flow of motivefluid for lifting liquid above the intermitting valve, said intermittingValve responsive to the pressure of the increased liquid for admittingmotive fluid into the eduction tubing and lifting liquid therefrom.

9. In a owing apparatus for wells, an eduction tubing extendingdownwardly into the well liquid, an inlet collar in the tubing foradmitting motive fluid, a plurality of vertically arranged differentialvalves extending downward from the collar in spaced relation in thetubing and providing a liquid choke below the collar, said valves in.fluid communication with the collar, an intermittlng valve associatedwith the collar and communicating therewith, said differential valveshaving a dual seating arrangement responsive to either hydrostatic headof liquid or pressure of motive iiuid for opening the valves to admitmotive fluid into the liquid stream and increase the height of theliquid level, said intermitting valve responsive to the increased liquidlevel for admitting motive fluid into the eduction tubing above thevalve and flowing the liquid to the surface.

10. In a owing apparatus for wells, an eduction tubing extendingdownwardly into the well liquid, an inlet collar in the tubing foradmitting motive iluid, a string of small tubing extending downward fromthe collar and in iiuid communication therewith, a plurality ofvertically arranged differential valves provided in the small tubing andarranged in spaced relation in the tubing and providing a choke belowthe collar, an intermitting valve associated with the collar andcommunicating therewith, said differential valves having a dual seatingarrangement responsive to either hydrostatic head of liquid or pressureof motive fluid for opening the valves to admit motive uid into theliquid stream and increase the height of the liquid level, saidintermitting valve responsive to the increased liquid level foradmitting motive fluid into the eduction tubing and flowing the liquidto the surface, and jetting means cooperating with the valve forincreasing the velocity of the discharging motive fluid.

11. In a flowing apparatus for wells, an eductiontubing extendingdownwardly into the Well liquid, an inlet collar in the tubing foradmitting motive fluid, a plurality of vertically arranged differentialvalves extending downward from the collar in spaced relation in thetubing and providing a choke below the collar, an intermitting valveassociated with the collar and communicating therewith, saiddifferential valves having a dual seating arrangement responsive toeither hydrostatic head of liquid or pressure of motive fluid foropening the valves to admit motive fluid into the liquid stream andincrease the height of the liquid level, said intermitting valveresponsive to the increased liquid level for admitting motive uid intothe eduction tubing and flowing the liquid to the surface, and outletmeans directing the motive fluid into the eduction tubing in a verticalpath upward.

12. A well flowing apparatus including a tubing for conducting liquidfrom the well, an inlet collar for motive fluid interposed in thetubing, a plurality of kick ofi valves arranged below the collar anddisposed in spaced relation in the tubing at successive elevations belowthe liquid level, said valves in fluid communication with the inletcollar an aerating valve disposed in the tubing above the collar andcommunicating therewith, said kick off valves successively responsive tothe motive fluid whereby the motive fluid forces the liquid from thestanding level in the well upward to a point in the tubing where thehydrostatic head of the liquid will move the aerating valve to a neutralposition for admitting motive fluid into the tubing above the aeratingvalve.

13. A well flowing apparatus including an eduction tubing for conductingliquid from the well, an inlet collar for motive fluid interposed in thetubing, a plurality of kick off valves interposed between strings ofsmaller tubing at successive elevations below the collar and in spacedrelation in the eduction tubing, said smaller tubing and kick off valvescommunicating with the collar and adapted to provide a choke for thenormal liquid level standing in the eduction tubing, an aerating valvedisposed in the eduction tubing above the collar, said kick off valvessuccessively responsive to motive uid whereby motive fluid pressureforces the liquid from the standing level in the well upward to anelevation in the eduction tubing above the collar, said aerating valveresponsive to the hydrostatic head of the lifted liquid for admittingmotive uid into the eduction tubing above the aerating valve.

14. A vwell flowing apparatus including an eduction tubing forconducting liquid from the well, an inlet collar for motive iuidinterposed in the tubing, a plurality of kick oli valves interposedbetween strings of smaller tubing at successive elevations below thecollar and in spaced relation in the eduction tubing, said smallertubing and kick off valves communicating with the collar and adapted toprovide a choke for the normal liquid level standing in the eductiontubing, an aerating valve disposed in the eduction tubing above thecollar, said kick olf valves successively responsive to motive fluidwhereby motive fluid pressure forces the liquid from the standing levelin the well upward to an elevation in the eduction tub-ing above thecollar, said aerating valve responsive to the hydrostatic head of thelifted liquid for admitting motive fluid into the eduction tubing abovethe aerating valve, and outlet means for directing the motive iiuid in avertical upward path.

15. A system for controlling the lifting of a well liquid including aneduction tubing disposed in a well, motive fluid inlet means interposedin the eduction tubing, means communicating with the inlet means andcontrolling the admission of the motive fluid into the liquid at a pointbelow the normal liquid level, said last mentioned means arranged inspaced relation in the eduction tubing and providing a choke fordecreasing the volume of liquid to be lifted, and differential meanscommunicating with and receiving motive fluid from the inlet meansdisposed normally above the liquid level and responsive to thehydrostatic head of liquid being lifted for admitting motive uid intothe eduction tubing and causing aerating of the liquid.

LYNN M. TRAWICK.

